Place 2 cups water, sugar substitute and mint in a small saucepan, bring to a boil and simmer for 10 minutes. Strain into a blender, discard mint. Thinly slice 1 cup of strawberries and set aside. Add 1/2 of the remaining strawberries to a blender and blend until smooth; pour into 2 quarter pitcher. Stir in sliced strawberries and remaining water. Add sugar to taste if needed, stirring until dissolved. Cover and chill until serving.